An Ancient Lake on Mars Was Able to Harbor a Variety of Lifeforms, Says SBU-Led Study

A Martian crater is providing more proof that the Red Planet may once have supported life, a Stony Brook geochemist and planetary scientist says in a recently published NASA study.

Sedimentary rocks from three locations on lower Mount Sharp on Mars examined by NASA’s Curiosity rover provide examples of different textures interpreted as sediments deposited at different depths within a long lived lake. This example exhibits thicker layers which occur at the edge of a lake where sediment-bearing water enters the lake, slows down and drops much of its sediment. Credit: NASA/JPL-Caltech/MSSS

The study led by Assistant Professor Joel Hurowitz offers perhaps the most significant evidence to date that an ancient lake on Mars had all the ingredients of a life-sustaining body of water.

Building on the 2013 discovery that Mars’ Gale crater contained a freshwater lake more than 3 billion years ago, Assistant Professor Joel Hurowitz led a team of 22 international scientists using findings beamed to Earth from NASA’s Curiosity rover to determine that the lake was stratified, meaning that depending on the depth, its water created several co-existing environments where life could flourish, much like the lakes on Earth.

Joel Hurowitz

“The diversity of environments in this Martian lake would have provided multiple opportunities for different types of microbes to survive, including those that thrive in oxidant-rich conditions, those that thrive in oxidant-poor conditions, and those that inhabit the interface between those settings,” Hurowitz said. “This type of oxidant stratification is a common feature of lakes on Earth, and now we’ve found it on Mars.”

Hurowitz is an assistant professor in Stony Brook’s Department of Geosciences, as well as the head of one of three laboratories inside the University’s Center for Planetary Exploration (CPEx), which brings students and faculty together to pave the way for future human exploration of our solar system through interdisciplinary study and hands-on science.

The study, titled Redox stratification of an ancient lake in Gale crater, Mars and published in the June 2 edition of Science, uses evidence retrieved by the Curiosity rover from the base of a mountain inside Gale crater. After examining the physical, chemical and mineral characteristics of the mountain’s rock layers, the team was able to not only determine that the ancient lake was stratified, but that ancient Mars itself experienced distinct climate change.

During the time Gale crater held lake water, climate conditions changed from colder and drier to warmer and wetter. This relatively short-term climate change took place within a longer climate evolution, during which Mars transitioned from warm, wet conditions that supported lakes, to the cold, arid planet we see through our telescopes today.

This diagram presents some of the processes and clues related to a long-ago lake on Mars that became stratified, with the shallow water richer in oxidants than deeper water was. Credit: NASA/JPL-Caltech/Stony Brook University

“These results give us unprecedented detail in answering questions about ancient environmental conditions on Mars,” said Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory. “I’m struck by how these fascinating conclusions on habitability and climate took everything the mission had to offer: a set of sophisticated science instruments, multiple years and miles of exploration, a landing site that retained a record of the ancient environment, and a lot of hard work by the mission team.”

While evidence of life on Mars is still unknown, seeking signs of life there starts with studying the environment and its ability, in present or ancient times, to sustain life. Developments such as these achieved by Hurowitz and all co-authors on the study reinforce NASA’s strategy to use rovers to further investigate Mars.